A heat transfer device usually comprises at least one warm tube for conducting a fluid containing or emitting heat and at least one cold tube for conducting a fluid absorbing heat. These tubes are coupled to each other in a heat-transferring manner so that heat from the fluid of the warm tube can be transferred into the fluid of the cold tube.
Here it is possible in principle to arrange at least one thermoelectric generator between warm tube and cold tube with the help of which electric energy can be generated from a heat flow or from a temperature difference. Such a thermoelectric generator corresponds to a Peltier element. With the Peltier element or with the thermoelectric generator, which can also be called TEG, a heat flow is generated from a voltage difference by utilising the Peltier effect. The reversal of this Peltier effect is the Seebeck effect, which generates an electric current from a temperature difference. In addition, semiconductors at different energy level are utilised with a TEG or Peltier element.
Since in the exhaust gas of a combustion engine a lot of waste heat is usually present it is possible, by using such a heat transfer device with at least one integrated TEG, to recover energy in form of heat and electric current. This energy can then be utilised elsewhere on the combustion engine or a vehicle equipped with such in order to improve the overall efficiency of the respective system.